1. Technical Field
The present invention relates to a piezoelectric device, in particular to a piezoelectric device having a piezoelectric resonator and an electronic component on a substrate.
2. Related Art
Piezoelectric devices having a piezoelectric resonator and an electronic component on a substrate are widely used in electronic equipment such as small sized information equipment. Recently, the size of the electronic equipment is increasingly reduced in height, and the piezoelectric device used in the electronic equipment is also required to have a lower height. JP-A-2000-31324 and JP-A-2007-201044 disclose examples of such a piezoelectric device having a reduced height. Disclosed in these documents is a piezoelectric device in which a quartz crystal resonator and an integrated circuit (IC) chip mounted on a substrate are molded with a sealant such as resin.
FIGS. 4A and 4B are diagrams schematically showing the structure of a related-art piezoelectric device. FIG. 4A is a side surface diagram, and FIG. 4B is a partially enlarged diagram of the device. Referring to the drawings, a piezoelectric device 1 includes a piezoelectric resonator 3 and an electronic component (IC chip) 4 mounted on the upper surface of a base substrate 2. A piezoelectric resonator element 5 is mounted in an internal space between a lid 9 and a package base 6. The package base 6 includes, from the lower layer, a flat plate substrate 7 and a frame-shaped substrate 9, in this order. When mounting the piezoelectric resonator 3 on the base substrate 2, an external electrode provided on the mounting surface of the flat plate substrate of the package base 6 is electrically coupled to a mounting electrode provided on the mounting surface of the base substrate 2.
In the piezoelectric device of the related art, however, because a component such as the piezoelectric resonator is mounted on the base substrate, the sum of the thickness of the package base of the piezoelectric resonator and the thickness of the base substrate becomes a total thickness d of the entire product, with reference to FIG. 4B. Therefore, even if a flat plate substrate constituting the package base is made thin, the height of the piezoelectric device is increased after all, because the sum of the thickness of the package base of the piezoelectric resonator and the thickness of the base substrate becomes the total thickness of the piezoelectric device. Accordingly, the reduction of height of the piezoelectric device has not been achieved.